The invention relates to musical instruments and more particularly to electronic keyboard musical instruments incorporating loudspeakers.
It is known from GB-A-2262861 to suggest a panel-form loudspeaker comprising:
a resonant multi-mode radiator element being a unitary sandwich panel formed of two skins of material with a spacing core of transverse cellular construction, wherein the panel is such as to have ratio of bending stiffness (S), in all orientations, to the cube power of panel mass per unit surface area (xcexc) of at least 10;
a mounting means which supports the panel or attaches to it a supporting body, in a free undamped manner;
and an electro-mechanical drive means coupled to the panel which serves to excite a multi-modal resonance in the radiator panel in response to an electrical input within a working frequency band for the loudspeaker.
WO-A-90/03025 of SCHIMMEL discloses a device for actuating the soundboard of a piano so that the piano can reproduce recorded piano music.
Embodiments of the present invention use members of nature, structure and configuration achievable generally and/or specifically by implementing teachings of our co-pending parent application Ser. No. 08/707,012, filed Sep. 3, 1996. Such members thus have capability to sustain and propagate input vibrational energy by bending waves in operative area(s) extending transversely of thickness often but not necessarily to edges of the member(s); are configured with or without anisotropy of bending stiffness to have resonant mode vibration components distributed over said area(s) beneficially for acoustic coupling with ambient air; and have predetermined preferential locations or sites within said area for transducer means, particularly operationally active or moving part(s) thereof effective in relation to acoustic vibrational activity in said area(s) and signals, usually electrical, corresponding to acoustic content of such vibrational activity. Uses are envisaged in parent application Ser. No. 08/707,012 for such members as or in xe2x80x9cpassivexe2x80x9d acoustic devices without transducer means, such as for reverberation or for acoustic filtering or for acoustically xe2x80x9cvoicingxe2x80x9d a space or room; and as or in xe2x80x9cactivexe2x80x9d acoustic devices with transducer means, such as in a remarkably wide range of sources of sound or loudspeakers when supplied with input signals to be converted to said sound, or in such as microphones when exposed to sound to be converted into other signals.
This invention is particularly concerned with electronic keyboard musical instruments incorporating active acoustic devices e.g. in the form of loudspeakers.
Members as above are herein called distributed mode radiators and are intended to be characterised as in the above parent application and/or otherwise as specifically provided herein.
The invention is an electronic musical instrument having a keyboard and a loudspeaker, characterised in that the loudspeaker comprises a stiff lightweight member having capability to sustain and propagate input vibrational energy by bending waves in at least one operative area extending transversely of thickness to have resonant mode vibration components distributed over said at least one area and have predetermined preferential locations or sites within said area for transducer means and having a transducer mounted wholly and exclusively on said member at one of said locations or sites to vibrate the member to cause it to resonate forming an acoustic radiator which provides an acoustic output when resonating. The radiator may have a cellular core sandwiched by a pair of high modulus skins. A frame may surround the radiator. A resilient suspension may support the radiator on the frame. The electronic musical instrument may comprise a body having a base and legs supporting the body above the ground, the radiator being positioned at the base of the body. The loudspeaker is positioned with the radiator substantially vertical. The frame may form a ground support for the instrument.